// Copyright (C) 2016 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qstatictext.h"

#include "qstatictext_p.h"

#include <qmath.h>

#include <private/qtextengine_p.h>

#include <private/qfontengine_p.h>

#include <qabstracttextdocumentlayout.h>

QT_BEGIN_NAMESPACE

QT_IMPL_METATYPE_EXTERN(QStaticText)

QStaticTextUserData::~QStaticTextUserData()

{

}

/*!

    \class QStaticText

    \brief The QStaticText class enables optimized drawing of text when the text and its layout

    is updated rarely.

    \since 4.7

    \inmodule QtGui

    \ingroup multimedia

    \ingroup text

    \ingroup shared

    QStaticText provides a way to cache layout data for a block of text so that it can be drawn

    more efficiently than by using QPainter::drawText() in which the layout information is

    recalculated with every call.

    The class primarily provides an optimization for cases where the text, its font and the

    transformations on the painter are static over several paint events. If the text or its layout

    is changed for every iteration, QPainter::drawText() is the more efficient alternative, since

    the static text's layout would have to be recalculated to take the new state into consideration.

    Translating the painter will not cause the layout of the text to be recalculated, but will cause

    a very small performance impact on drawStaticText(). Altering any other parts of the painter's

    transformation or the painter's font will cause the layout of the static text to be

    recalculated. This should be avoided as often as possible to maximize the performance

    benefit of using QStaticText.

    In addition, only affine transformations are supported by drawStaticText(). Calling

    drawStaticText() on a projected painter will perform slightly worse than using the regular

    drawText() call, so this should be avoided.

    \code

    class MyWidget: public QWidget

    {

    public:

        MyWidget(QWidget *parent = nullptr) : QWidget(parent), m_staticText("This is static text")

    protected:

        void paintEvent(QPaintEvent *)

        {

            QPainter painter(this);

            painter.drawStaticText(0, 0, m_staticText);

        }

    private:

        QStaticText m_staticText;

    };

    \endcode

    The QStaticText class can be used to mimic the behavior of QPainter::drawText() to a specific

    point with no boundaries, and also when QPainter::drawText() is called with a bounding

    rectangle.

    If a bounding rectangle is not required, create a QStaticText object without setting a preferred

    text width. The text will then occupy a single line.

    If you set a text width on the QStaticText object, this will bound the text. The text will

    be formatted so that no line exceeds the given width. The text width set for QStaticText will

    not automatically be used for clipping. To achieve clipping in addition to line breaks, use

    QPainter::setClipRect(). The position of the text is decided by the argument passed to

    QPainter::drawStaticText() and can change from call to call with a minimal impact on

    performance.

    For extra convenience, it is possible to apply formatting to the text using the HTML subset

    supported by QTextDocument. QStaticText will attempt to guess the format of the input text using

    Qt::mightBeRichText(), and interpret it as rich text if this function returns \c true. To force

    QStaticText to display its contents as either plain text or rich text, use the function

    QStaticText::setTextFormat() and pass in, respectively, Qt::PlainText and Qt::RichText.

    QStaticText can only represent text, so only HTML tags which alter the layout or appearance of

    the text will be respected. Adding an image to the input HTML, for instance, will cause the

    image to be included as part of the layout, affecting the positions of the text glyphs, but it

    will not be displayed. The result will be an empty area the size of the image in the output.

    Similarly, using tables will cause the text to be laid out in table format, but the borders

    will not be drawn.

    If it's the first time the static text is drawn, or if the static text, or the painter's font

    has been altered since the last time it was drawn, the text's layout has to be

    recalculated. On some paint engines, changing the matrix of the painter will also cause the

    layout to be recalculated. In particular, this will happen for any engine except for the

    OpenGL2 paint engine. Recalculating the layout will impose an overhead on the

    QPainter::drawStaticText() call where it occurs. To avoid this overhead in the paint event, you

    can call prepare() ahead of time to ensure that the layout is calculated.

    \sa QPainter::drawText(), QPainter::drawStaticText(), QTextLayout, QTextDocument

*/

/*!

    \enum QStaticText::PerformanceHint

    This enum the different performance hints that can be set on the QStaticText. These hints

    can be used to indicate that the QStaticText should use additional caches, if possible,

    to improve performance at the expense of memory. In particular, setting the performance hint

    AggressiveCaching on the QStaticText will improve performance when using the OpenGL graphics

    system or when drawing to a QOpenGLWidget.

    \value ModerateCaching Do basic caching for high performance at a low memory cost.

    \value AggressiveCaching Use additional caching when available. This may improve performance

           at a higher memory cost.

*/

/*!

    Constructs an empty QStaticText

*/

QStaticText::QStaticText()

    : data(new QStaticTextPrivate)

{

}

/*!

    Constructs a QStaticText object with the given \a text.

*/

QStaticText::QStaticText(const QString &text)

    : data(new QStaticTextPrivate)

{

    data->text = text;

    data->invalidate();

}

/*!

    Constructs a QStaticText object which is a copy of \a other.

*/

QStaticText::QStaticText(const QStaticText &other)

{

    data = other.data;

}

/*!

    Destroys the QStaticText.

*/

QStaticText::~QStaticText()

{

    Q_ASSERT(!data || data->ref.loadRelaxed() >= 1);

}

/*!

    \internal

*/

void QStaticText::detach()

{

    if (data->ref.loadRelaxed() != 1)

        data.detach();

}

/*!

  Prepares the QStaticText object for being painted with the given \a matrix and the given \a font

  to avoid overhead when the actual drawStaticText() call is made.

  When drawStaticText() is called, the layout of the QStaticText will be recalculated if any part

  of the QStaticText object has changed since the last time it was drawn. It will also be

  recalculated if the painter's font is not the same as when the QStaticText was last drawn, or,

  on any other paint engine than the OpenGL2 engine, if the painter's matrix has been altered

  since the static text was last drawn.

  To avoid the overhead of creating the layout the first time you draw the QStaticText after

  making changes, you can use the prepare() function and pass in the \a matrix and \a font you

  expect to use when drawing the text.

  \sa QPainter::setFont(), QPainter::setWorldTransform()

*/

void QStaticText::prepare(const QTransform &matrix, const QFont &font)

{

    data->matrix = matrix;

    data->font = font;

    data->init();

}

/*!

    Assigns \a other to this QStaticText.

*/

QStaticText &QStaticText::operator=(const QStaticText &other)

{

    data = other.data;

    return *this;

}

/*!

    \fn void QStaticText::swap(QStaticText &other)

    \since 5.0

    \memberswap{static text instance}

*/

/*!

    Compares \a other to this QStaticText. Returns \c true if the texts, fonts and text widths

    are equal.

*/

bool QStaticText::operator==(const QStaticText &other) const

{

    return (data == other.data

            || (data->text == other.data->text

                && data->font == other.data->font

                && data->textWidth == other.data->textWidth));

}

/*!

    Compares \a other to this QStaticText. Returns \c true if the texts, fonts or maximum sizes

    are different.

*/

bool QStaticText::operator!=(const QStaticText &other) const

{

    return !(*this == other);

}

/*!

    Sets the text of the QStaticText to \a text.

    \note This function will cause the layout of the text to require recalculation.

    \sa text()

*/

void QStaticText::setText(const QString &text)

{

    detach();

    data->text = text;

    data->invalidate();

}

/*!

   Sets the text format of the QStaticText to \a textFormat. If \a textFormat is set to

   Qt::AutoText (the default), the format of the text will try to be determined using the

   function Qt::mightBeRichText(). If the text format is Qt::PlainText, then the text will be

   displayed as is, whereas it will be interpreted as HTML if the format is Qt::RichText. HTML tags

   that alter the font of the text, its color, or its layout are supported by QStaticText.

   \note This function will cause the layout of the text to require recalculation.

   \sa textFormat(), setText(), text()

*/

void QStaticText::setTextFormat(Qt::TextFormat textFormat)

{

    detach();

    data->textFormat = textFormat;

    data->invalidate();

}

/*!

  Returns the text format of the QStaticText.

  \sa setTextFormat(), setText(), text()

*/

Qt::TextFormat QStaticText::textFormat() const

{

    return Qt::TextFormat(data->textFormat);

}

/*!

    Returns the text of the QStaticText.

    \sa setText()

*/

QString QStaticText::text() const

{

    return data->text;

}

/*!

  Sets the performance hint of the QStaticText according to the \a

  performanceHint provided. The \a performanceHint is used to

  customize how much caching is done internally to improve

  performance.

  The default is QStaticText::ModerateCaching.

  \note This function will cause the layout of the text to require recalculation.

  \sa performanceHint()

*/

void QStaticText::setPerformanceHint(PerformanceHint performanceHint)

{

    if ((performanceHint == ModerateCaching && !data->useBackendOptimizations)

        || (performanceHint == AggressiveCaching && data->useBackendOptimizations)) {

        return;

    }

    detach();

    data->useBackendOptimizations = (performanceHint == AggressiveCaching);

    data->invalidate();

}

/*!

  Returns which performance hint is set for the QStaticText.

  \sa setPerformanceHint()

*/

QStaticText::PerformanceHint QStaticText::performanceHint() const

{

    return data->useBackendOptimizations ? AggressiveCaching : ModerateCaching;

}

/*!

   Sets the text option structure that controls the layout process to the given \a textOption.

   \sa textOption()

*/

void QStaticText::setTextOption(const QTextOption &textOption)

{

    detach();

    data->textOption = textOption;

    data->invalidate();

}

/*!

    Returns the current text option used to control the layout process.

*/

QTextOption QStaticText::textOption() const

{

    return data->textOption;

}

/*!

    Sets the preferred width for this QStaticText. If the text is wider than the specified width,

    it will be broken into multiple lines and grow vertically. If the text cannot be split into

    multiple lines, it will be larger than the specified \a textWidth.

    Setting the preferred text width to a negative number will cause the text to be unbounded.

    Use size() to get the actual size of the text.

    \note This function will cause the layout of the text to require recalculation.

    \sa textWidth(), size()

*/

void QStaticText::setTextWidth(qreal textWidth)

{

    detach();

    data->textWidth = textWidth;

    data->invalidate();

}

/*!

    Returns the preferred width for this QStaticText.

    \sa setTextWidth()

*/

qreal QStaticText::textWidth() const

{

    return data->textWidth;

}

/*!

  Returns the size of the bounding rect for this QStaticText.

  \sa textWidth()

*/

QSizeF QStaticText::size() const

{

    if (data->needsRelayout)

        data->init();

    return data->actualSize;

}

QStaticTextPrivate::QStaticTextPrivate()

        : textWidth(-1.0), items(nullptr), itemCount(0), glyphPool(nullptr), positionPool(nullptr),

          needsRelayout(true), useBackendOptimizations(false), textFormat(Qt::AutoText),

          untransformedCoordinates(false)

{

}

QStaticTextPrivate::QStaticTextPrivate(const QStaticTextPrivate &other)

    : text(other.text), font(other.font), textWidth(other.textWidth), matrix(other.matrix),

      items(nullptr), itemCount(0), glyphPool(nullptr), positionPool(nullptr), textOption(other.textOption),

      needsRelayout(true), useBackendOptimizations(other.useBackendOptimizations),

      textFormat(other.textFormat), untransformedCoordinates(other.untransformedCoordinates)

{

}

QStaticTextPrivate::~QStaticTextPrivate()

{

    delete[] items;

    delete[] glyphPool;

    delete[] positionPool;

}

QStaticTextPrivate *QStaticTextPrivate::get(const QStaticText *q)

{

    return q->data.data();

}

namespace {

    class DrawTextItemRecorder: public QPaintEngine

    {

    public:

        DrawTextItemRecorder(bool untransformedCoordinates, bool useBackendOptimizations)

                : m_dirtyPen(false), m_useBackendOptimizations(useBackendOptimizations),

                  m_untransformedCoordinates(untransformedCoordinates), m_currentColor(0, 0, 0, 0)

        {

        }

        virtual void updateState(const QPaintEngineState &newState) override

        {

            if (newState.state() & QPaintEngine::DirtyPen

                && newState.pen().color() != m_currentColor) {

                m_dirtyPen = true;

                m_currentColor = newState.pen().color();

            }

        }

        virtual void drawTextItem(const QPointF &position, const QTextItem &textItem) override

        {

            const QTextItemInt &ti = static_cast<const QTextItemInt &>(textItem);

            QStaticTextItem currentItem;

            currentItem.setFontEngine(ti.fontEngine);

            currentItem.font = ti.font();

            currentItem.glyphOffset = m_glyphs.size(); // Store offset into glyph pool

            currentItem.positionOffset = m_glyphs.size(); // Offset into position pool

            currentItem.useBackendOptimizations = m_useBackendOptimizations;

            if (m_dirtyPen)

                currentItem.color = m_currentColor;

            QTransform matrix = m_untransformedCoordinates ? QTransform() : state->transform();

            matrix.translate(position.x(), position.y());

            QVarLengthArray<glyph_t> glyphs;

            QVarLengthArray<QFixedPoint> positions;

            ti.fontEngine->getGlyphPositions(ti.glyphs, matrix, ti.flags, glyphs, positions);

            int size = glyphs.size();

            Q_ASSERT(size == positions.size());

            currentItem.numGlyphs = size;

            m_glyphs.resize(m_glyphs.size() + size);

            m_positions.resize(m_glyphs.size());

            glyph_t *glyphsDestination = m_glyphs.data() + currentItem.glyphOffset;

            memcpy(glyphsDestination, glyphs.constData(), sizeof(glyph_t) * currentItem.numGlyphs);

            QFixedPoint *positionsDestination = m_positions.data() + currentItem.positionOffset;

            memcpy(positionsDestination, positions.constData(), sizeof(QFixedPoint) * currentItem.numGlyphs);

            m_items.append(currentItem);

        }

        virtual void drawPolygon(const QPointF *, int , PolygonDrawMode ) override

        {

            /* intentionally empty */

        }

        virtual bool begin(QPaintDevice *) override  { return true; }

        virtual bool end() override { return true; }

        virtual void drawPixmap(const QRectF &, const QPixmap &, const QRectF &) override {}

        virtual Type type() const override

        {

            return User;

        }

        QList<QStaticTextItem> items() const

        {

            return m_items;

        }

        QList<QFixedPoint> positions() const

        {

            return m_positions;

        }

        QList<glyph_t> glyphs() const

        {

            return m_glyphs;

        }

    private:

        QList<QStaticTextItem> m_items;

        QList<QFixedPoint> m_positions;

        QList<glyph_t> m_glyphs;

        bool m_dirtyPen;

        bool m_useBackendOptimizations;

        bool m_untransformedCoordinates;

        QColor m_currentColor;

    };

    class DrawTextItemDevice: public QPaintDevice

    {

    public:

        DrawTextItemDevice(bool untransformedCoordinates, bool useBackendOptimizations)

        {

            m_paintEngine = new DrawTextItemRecorder(untransformedCoordinates,

                                                     useBackendOptimizations);

        }

        ~DrawTextItemDevice()

        {

            delete m_paintEngine;

        }

        int metric(PaintDeviceMetric m) const override

        {

            int val;

            switch (m) {

            case PdmWidth:

            case PdmHeight:

            case PdmWidthMM:

            case PdmHeightMM:

                val = 0;

                break;

            case PdmDpiX:

            case PdmPhysicalDpiX:

                val = qt_defaultDpiX();

                break;

            case PdmDpiY:

            case PdmPhysicalDpiY:

                val = qt_defaultDpiY();

                break;

            case PdmNumColors:

                val = 16777216;

                break;

            case PdmDepth:

                val = 24;

                break;

            case PdmDevicePixelRatio:

                val = 1;

                break;

            case PdmDevicePixelRatioScaled:

                val = devicePixelRatioFScale();

                break;

            default:

                val = 0;

                qWarning("DrawTextItemDevice::metric: Invalid metric command");

            }

            return val;

        }

        virtual QPaintEngine *paintEngine() const override

        {

            return m_paintEngine;

        }

        QList<glyph_t> glyphs() const

        {

            return m_paintEngine->glyphs();

        }

        QList<QFixedPoint> positions() const

        {

            return m_paintEngine->positions();

        }

        QList<QStaticTextItem> items() const

        {

            return m_paintEngine->items();

        }

    private:

        DrawTextItemRecorder *m_paintEngine;

    };

}

void QStaticTextPrivate::paintText(const QPointF &topLeftPosition, QPainter *p, const QColor &pen)

{

    bool preferRichText = textFormat == Qt::RichText

                          || (textFormat == Qt::AutoText && Qt::mightBeRichText(text));

    if (!preferRichText) {

        QTextLayout textLayout;

        textLayout.setText(text);

        textLayout.setFont(font);

        textLayout.setTextOption(textOption);

        textLayout.setCacheEnabled(true);

        qreal height = 0;

        textLayout.beginLayout();

        while (1) {

            QTextLine line = textLayout.createLine();

            if (!line.isValid())

                break;

            line.setLeadingIncluded(true);

            if (textWidth >= 0.0)

                line.setLineWidth(textWidth);

            else

                line.setLineWidth(QFIXED_MAX);

            line.setPosition(QPointF(0.0, height));

            height += line.height();

            if (line.leading() < 0)

                height += qCeil(line.leading());

        }

        textLayout.endLayout();

        actualSize = textLayout.boundingRect().size();

        p->setPen(pen);

        textLayout.draw(p, topLeftPosition);

    } else {

        QTextDocument document;

#ifndef QT_NO_CSSPARSER

        document.setDefaultStyleSheet(QString::fromLatin1("body { color: rgba(%1, %2, %3, %4%) }")

                                      .arg(QString::number(pen.red()))

                                      .arg(QString::number(pen.green()))

                                      .arg(QString::number(pen.blue()))

                                      .arg(QString::number(pen.alpha())));

#endif

        document.setDefaultFont(font);

        document.setDocumentMargin(0.0);

#ifndef QT_NO_TEXTHTMLPARSER

        document.setHtml(text);

#else

        document.setPlainText(text);

#endif

        if (textWidth >= 0.0)

            document.setTextWidth(textWidth);

        else

            document.adjustSize();

        document.setDefaultTextOption(textOption);

        p->save();

        p->translate(topLeftPosition);

        QAbstractTextDocumentLayout::PaintContext ctx;

        ctx.palette.setColor(QPalette::Text, pen);

        document.documentLayout()->draw(p, ctx);

        p->restore();

        actualSize = document.size();

    }

}

void QStaticTextPrivate::init()

{

    delete[] items;

    delete[] glyphPool;

    delete[] positionPool;

    position = QPointF(0, 0);

    DrawTextItemDevice device(untransformedCoordinates, useBackendOptimizations);

    {

        QPainter painter(&device);

        painter.setFont(font);

        painter.setTransform(matrix);

        paintText(QPointF(0, 0), &painter, QColor(0, 0, 0, 0));

    }

    QList<QStaticTextItem> deviceItems = device.items();

    QList<QFixedPoint> positions = device.positions();

    QList<glyph_t> glyphs = device.glyphs();

    itemCount = deviceItems.size();

    items = new QStaticTextItem[itemCount];

    glyphPool = new glyph_t[glyphs.size()];

    memcpy(glyphPool, glyphs.constData(), glyphs.size() * sizeof(glyph_t));

    positionPool = new QFixedPoint[positions.size()];

    memcpy(positionPool, positions.constData(), positions.size() * sizeof(QFixedPoint));

    for (int i=0; i<itemCount; ++i) {

        items[i] = deviceItems.at(i);

        items[i].glyphs = glyphPool + items[i].glyphOffset;

        items[i].glyphPositions = positionPool + items[i].positionOffset;

    }

    needsRelayout = false;

}

QT_END_NAMESPACE